The present invention relates to remote actuating apparatus and more particularly, to improvements in security coding provided by such apparatus.
Remote actuating apparatus such as automatic garage door openers, comprise remote transmitters and a receiver which responds to signals from the transmitters to generate actuating signals thereby opening a door. The receivers of such arrangements provide security in their operation by actuating only when a properly transmitted request is received which matches one of a small number of allowable security codes. The security codes are used to deny access by miscreants and to limit the possibility that someone with a similar transmitter will erroneously open garage doors other than his or her own.
Modern remote actuation systems provide for tens of thousands of unique security codes and the probability of a neighbor using the same code or of a potential criminal "breaking" a code are relatively small. Consumer demands for security improvements are growing, however. One possible response to such demands is to increase the number of coded characters in the security codes. This improves security, but it creates a number of additional problems. One problem comes about from the security code set up arrangements of today's door openers. Most rely on the set up by a user of a number of tiny switches in each transmitter. When the number of code characters is increased, the number of switches to be provided also increases, causing physical design problems in the transmitter and given the size of the switches makes the system more difficult to set up by the user.
An alternative to providing switched code settings in transmitters is to assign each transmitter a unique code which is unchangeably stored in the transmitter. Such a permanent code, when combined with a programmable receiver, as is disclosed in C. Heitschel, et al., U.S. Pat. No. 4,750,118; makes set up an easy task but it makes impossible the selective use of a single transmitter with more than one receiver when the receivers are physically close enough that they both receive the same transmissions. A need exists for a remote actuating system which provides set up convenience, but in which a single transmitter can operate selectively with multiple receivers.
Adding to the number of security code characters also requires a new transmission and reception format. The adoption of a new format without proper consideration for the old format makes obsolete many old transmitters. Such forced obsolescence is not desirable. Accordingly, a need exists for a new coding format which permits the desired increases in security, while at the same time is compatible with equipment which is presently in the hands of consumers.